Browsing by Subject "Fluoranthene"

Now showing 1 - 4 of 4

Open Access
Cyclodextrin-functionalized mesostructured silica nanoparticles for removal of polycyclic aromatic hydrocarbons
(Academic Press Inc., 2017) Topuz, F.; Uyar, T.
Polycyclic aromatic hydrocarbons (PAHs) are the byproducts of the incomplete combustion of carbon-based fuels, and have high affinity towards DNA strands, ultimately exerting their carcinogenic effects. They are ubiquitous environmental contaminants, and can accumulate on tissues due to their lipophilic nature. In this article, we describe a novel concept for PAH removal from aqueous solutions using cyclodextrin-functionalized mesostructured silica nanoparticles (CDMSNs) and pristine mesostructured silica nanoparticles (MSNs). The adsorption applications of MSNs are greatly restricted due to the absence of surface functional groups on such particles. In this regard, cyclodextrins can serve as ideal functional molecules with their toroidal, cone-type structure, capable of inclusion-complex formation with many hydrophobic molecules, including genotoxic PAHs. The CDMSNs were synthesized by the surfactant-templated, NaOH-catalyzed condensation reactions of tetraethyl orthosilicate (TEOS) in the presence of two different types of cyclodextrin (i.e. hydroxypropyl-β-cyclodextrin (HP-β-CD) and native β-cyclodextrin (β-CD)). The physical incorporation of CD moieties was supported by XPS, FT-IR, NMR, TGA and solid-state 13C NMR. The CDMSNs were treated with aqueous solutions of five different PAHs (e.g. pyrene, anthracene, phenanthrene, fluorene and fluoranthene). The functionalization of MSNs with cyclodextrin moieties significantly boosted the sorption capacity (q) of the MSNs up to ∼2-fold, and the q ranged between 0.3 and 1.65 mg per gram CDMSNs, of which the performance was comparable to that of the activated carbon.
Open Access
Poly-cyclodextrin cryogels with aligned porous structure for removal of polycyclic aromatic hydrocarbons (PAHs) from water
(Elsevier, 2017-08) Topuz, F.; Uyar, Tamer
Cyclodextrins (CDs) are sugar-based cyclic oligosaccharides, which form inclusion complexes with small guest molecules through their hydrophobic cavity. Here we successfully synthesized highly porous poly-cyclodextrin (poly-CD) cryogels, which were produced under cryogenic conditions by the cross-linking of amine-functional CDs with PEG-based diepoxide cross-linker. The poly-CD cryogels showed aligned porous network structures owing to the directional freezing of the matrix, of which the pore size and architecture exposed variations depending on the composition of the reactants. The cryogels were employed for the removal of genotoxic polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. They reached PAH sorption capacities as high as 1.25 mg PAH per gram cryogel. This high sorption performance is due to interactions between PAHs and the complete swollen network, and thus, is not restricted by interfacial adsorption. Given that the hydrophilic nature of the components, the sorption performance could only be attributed to the inclusion complex formation of CDs with PAH molecules. The poly-CD cryogels could be recycled with an exposure to ethanol and reused without any significant loss in the sorption capacity of PAHs.
Open Access
Total synthesis of biologically active fungal natural products daldiquinone and bulgarein, and intramolecular Diels-Alder reactions for fluoranthene synthesis
(2021-06) Ahmadlı, Dilgam
Natural products continue to play a significant role in drug discovery and be a substantial source for novel pharmaceutical drugs. Total synthesis of biologically active natural products is critical for deciphering how natural products regulate cellular and other biological processes and, structure determination. In addition, the total synthesis of natural products has also been a stimulus for the discovery of new methodologies and reactions. The fungal natural product daldiquinone (15), which possesses a highly oxidized binaphthyl skeleton, was isolated in 2018 from Daldinia concéntrica, and was shown to have antiangiogenesis activity against HUVECs with an IC50 value of 7.5 M. Another fungal natural product bulgarein (1) was first isolated in 1976 from the fungus Bulgaria inquinans, and was shown to induce topoisomerase I-mediated DNA cleavage. However, as in the case of daldiquinone (15), total synthesis of bulgarein (1) has yet to be reported. In this work, we report the first total syntheses of daldiquinone (15) and bulgarein (1) starting from the commercially available 1,8-DHN (1,8-dihydroxynaphthalene, 1,8-naphthalenediol) via a concise route. Pd-catalyzed Suzuki coupling and C-H arylation reactions between functionalized naphthalenes and hypervalent iodine-mediated double oxidation of phenol to o-quinone were employed as key steps. Thanks to their thermal stability and electronic properties, fluoranthene derivatives have widespread medicinal chemistry and organic optoelectronics applications. A significant number of fluoranthene-based natural products are known, including bulgarein (1). Although many procedures have been developed to synthesize fluoranthenes, practical and modular strategy for synthesizing many substituted unsymmetrical fluoranthenes is still desirable. In this work, we report a novel approach to achieve modular syntheses of fluoranthene derivatives based on intramolecular Diels-Alder reaction.
Open Access
Transition metal catalysis for aerobic C-H oxidation reactions and for the synthesis of fluoranthene derivatives
(2021-01) Şahin, Yeşim
Within the past two decades, a powerful class of new reactions that introduces oxidized functionality to (sp3) C-H bonds has emerged and gained tremendous attention since it can revolutionize the chemical industry by placing reactive functional groups directly in a molecule. Usually, precious metals (e.g., Pd, Pt, Ru etc.) are used for the activation of C-H bonds, and finding alternative ways that use less expensive and less toxic first row transition metals to replace precious metal catalysts is necessary. In this work, we have developed a reductive pretreatment system to increase the activity of precious metal-free LaMnO3 perovskites for C-H oxidation reactions of alkylarenes to ketones or oxidative dimerization of naphthols under mild conditions. Furthermore, a bimetallic nickel-manganese based hydroxide catalyst was synthesized as well and it was proven to oxidize a variety of alkylarenes and alcohols. Using molecular oxygen as the sole oxidant in C-H oxidation reactions is another advantage of our method since it is green, inexpensive and readily available in nature. In the second part, two novel methods have been developed for the synthesis of fluoranthenes which are important polycyclic skeletons. They can be found in many natural products, organic electronics, dyes and various materials. These methods employ Pd-catalyzed cross-coupling reactions such as Suzuki-Miyaura and Sonogashira reactions in the first steps using 1,8-dihalonaphthalenes and then use intramolecular Diels-Alder reactions for the formation of tetracyclic ring in the fluoranthene core. Our methods also provide a modular pathway for the synthesis of multi-substituted fluoranthene derivatives from simple molecules because it is designed as a three-component system and each component can be readily prepared or functionalized allowing easy modification.